Air brake



G. A. CAMPBELL.

AIR BRAKE Filed March 6. 1926 2 Sheets-Sheet l e s. dmw

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Patented Dec. 27, 1927.

STATES PArENr ourlet.

@H dltlhES ALBERT CAMPBELL, OF WATERTOWN, NEW-YORK, ASSIGNOR 'l'.'O THE NEW "YORK AIR BRAKE COMPANY, A CORPORATION OF NEW' JEREMY.,

AIR BRAKE.

Vlhis invention relates to fluid pressure brakes, and particularly to that type of air brake operating at sub-atmospheric pressure and commonly called vacuum brakes.

'lhe object of the invention is to produce a brake oit this type peculiarly adapted for use on a motor vehicle propelled by a gasolene engine and available for use not only on the motor propelled vehicle but also on a trailer drawn thereby.

'lhe vacuum type ot' brake is peculiarly adapted Jtor this lield ot use for two reasons. ln the hrst place, a simple connection to the intake manifold ot the engine suilices as a l" means for developing the sub-atmospheric pressure needed in the operation of the brake. ln the second place there is no tendency tor moisture to condense in the brake system. 'l'his last is a constant source ot trouble in high pressure brakes and is peculiarly troublesome on motor road vehicles because the brake apparatus is exposed and readily freezes up when any moisture iS present.

Generally stated, brakes are operated by pistouswhich in release condition are subject on both sides to sub-atmospheric pressure. ln application position communication between opposite sides ot the piston is interrupted and air under atmospheric pressure is admitted to act on one side oit the piston.

ln order to secure the desired flexibility a reservoir maintained at the desired sub-atmospheric pressure is included in the system, and asimilar reservoir is used on the trailer so that in case oit a break-in-two the 'trailer brakes will apply.

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' Application led March 6, 1926. Serial No. 958,853.

positions, is in edect merely a shitting valve seat and carries two ports. @ne of these ports is constantly connected with vone end of the brake cylinder, and with the actuating cylinder for the riding valve hereinafter L described. The other port is constantly connected with sub-atmospheric pressure reservoir and with the other end ot the brake cylinder. Co-acting with the main valve is a graduating slide valve. ln one position relatively to the main slide valve this riding valve connects the ports in the main valve together and thus places both ends of the bra-ke cylinder in communication with the sub-atmospheric pressure reservoir. ln another position it interrupts the connection between two ports in the main valve and admits atmospheric air to one or them to apply the brakes. There is an intermediate lap position in which the admission ot atmospheric pressure is interrupted without howeverl establishing communication with the two ends of the brake cylinder.

The riding valve is actuated by a piston which is subject in one direction to atmospheric pressure Vtending to open the valve and produce an application, and in the other direction to brake cylinder pressure assisted by a spring tending to close or lap the valve and restore release conditions. Thus the position of the riding valve is directly proportional to the brake cylinder pressure.

lt will be obvious trom an inspection ot the drawings that the ehiect is 'to establish in the brake cylinder definite pressures corresponding to detinite positions ot the main valve and to graduate the pressure on and od' at will. lllhere the brake valve is actuated by a loot pedal this may he provided with a return spring", so that in operating the toot pedal the action oit an ordinary mechanical loot brake is closely simulated etn1 cept that the torce eirerted on the pedal isV less.'

Another feature oir' the invention is that the main valve is given a range oi movement slightly greater than that ont the graduating valve. f"l`hiis in the entreme applica,- tion position ont the main valve it is impossible itor the riding 'valve to lap the admirtitl Sti

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sion port, the range of motion being insullicient. This insures a full application upon full depression of the pedal without an disturbing action of the graduating va ve. 4 I

In the drawings is illustrated, largely in diagram, a practical embodiment of the invention. In the drawings- Figure 1 is a diagrammatic view, largely sectional, vshowing the complete installation on a motor vehicle and trailer. In this view Figure 6 is a diagram showing theparts in release lap position. The arrow in this ligure indicates the direction which` the riding valve moved to lap position.l

Figure 7 is a view,partly'1nsection, and partly in elevation, showin the hose coupling between" the truck an trailer in normal connective position 0n the reservoir p1 e.

igure 8 is 'a similar view showing t e position assumed by the parts of the hose connection in case of a break-in-two.

In the drawings, 11 is the manifold of an internal combustion engine of the type in which the engine draws in its own charges Aby suction. A common gasolene automobile engine is a familiar example of this type'. 12 indicates the'carburetor. A sub-atmospheric pressure reservoir 13 is connected by a pipe 14 through ay check valve 15 with the intake passage, preferably between the carburetor 12 and the manifold 11. Check valve 15 opens toward the manifold and when the engine is running it operates to reduce the absolutepressure in the reservoir, 13. It is possible in this way to secure in the reservoir 13 a barometric pressure, as much as 24 inches of mercury below atmos heric In any event it is possi le to maintain continuously in the reservoir'13 a pressure'substantially below atmospheric and the dierence between this and atmospheric pressure is adequate for the operation of the rakes. The reservoir 13 has a connection 16 coni trolled by a stop valve 17, and leading to a reservoir line 1'8. This reservoir line is connected at 19 with the .head end of a brake cylinder 20, whose piston 21 is provided with a rolling packing ring22, and is urged in aA releasing direction, i. e., awa from the head end, by a coil-spring 23. e opposite end of the cylinder 20 is also closed and is Vprovided with-a stuiing box 24, through which passes a piston rod 25 connected to the brake rigging (not shown) by a link 26. The connections are such that when the piston 21 moves toward the head end (i. e., toward the right in Figure 1) the brakes will be applied. The reservoir line 18 is connected by flexible hose 27 and releasable couplings 28, 29 with .a reservoir line 30, on the trailing vehicle. The line 30 is connected to a supplemental reservoir 3l carried by the trailing vehicle, and is also connected at 32 with the head end of a brake cylinder 20* identical with that on the motor vehicle. The parts of this brake cylinder are similarly numbered but with the subscript a, and require no further description.

Leading from the cock 17 and in open communication with the reservoir line 18, is a connection 34 leading to the casing 35 of the brake valve. This valve casing is provided with a valve seat 36 and connection 34 communicates with a port 37 terminating in this valve seat. A second port 38 also in this valve seat communicates with the :.onnection 39 -leading to the brake ipe 40, which is connected at 41 with the le t end of the brake cvlinder 20. The brake pipe 40 is connected by hose 42 and detachable couplings generallyrindicatedby the numerals 43, 44, with the brake pipe 45, on the trailing vehicle. This is connected at. 46 with .the left end of the brake cylinder 20 on such vehicle.

The couplings 43 and 44 as clearly shown in Figure 7 carry each a latch nose 47, and each a latch member 48 designed to engage with the'latch nose47 of the other to maintain the two couplings together sov that n sea-led connection is produced by the gaskets 49. The latch members 48 are pivoted at 50 in lugs 51 and are urged in engaging direction by springs 52.

Each latch member 48 is formed with an extension 53 which under the urge of its spring 52 serves as a flapY valve to seal against the corresponding gasket 49, and prevent the entrance of air when the two couplings are pulled apart. As shown in Figure 8', the member 53 on the trailer coupling 43 is provided with a relatively small admission The couplings 28 and 29 on the reservoirr lineare both identical with the coupling 44, 1. e., they are devoid of the port 54 and close immediately upon a break-in-two or separation of the coupling, to maintain the reduced pressure inthe reservoirs 13 and 31.

The valve casing is provided with a removable top half or cover 56, which is provided with an air inlet connection 57 equipped with a strainer 58. This strainer is shown as consisting of curled hair enclosed in a chamber, but may be constructed in any preferred manner. All the air. admitted to the system enters at this point, and it is important to minimize the entrance of dust and grit.

Sliding on the valve seat 36 is a` main valve 59. This has an upstanding lug 60 provided with a roller 61.. The roller is engaged by the Ait'orlred end of the lever 62 plvoted as at 63 in a cover 56 and actuated by a reach rod 64, which is connected to the brake pedal lever 65. The lever 65 is drawn rearward or in release direction by a spring 67. VVhifle l show a Vfoot pedal, obviously the lever 65 might be operated in any suitable manner.

Spring 67 causes the pedal to act in a manner similar to that characteristic of conventional mechanical brake pedals, but it it were desired to operate the lever 65 manually in both directions, the spring 67 could be omitted. i v

It follows from the connection above describedl that the valve 59 assumes a series of positions corresponding to a series of positions of the :toot lever 65. It is formed on its lower face with a recess 68, which always is in communication with port 38, and with a second recess 69, which is always in communication with port 37. From the recess .68 a port 70 leads to the top face of the valve 59 and from the recess 69 a second port 71 leads to the top face of the valve 59.

lThus the eiect of moving the valve 59 is merely to displace the ports 7 0 and 7l simultaneously a corresponding amount.

'a recess 73 on its lower face.

Mounted on the top of the main valve 59 is a graduatingvalve 72, which is formed with In release position the recess 73 connects the ports 70 and 71. In application position the valve 72 clears the port 70 and allows air entering through the strainer 58 inconnection 57 to flow through the port 70 and thence by space to the right ofthe piston 75vis connected by a port 78 with the port 38 and hence with the left end of the brake cylinders 20, 20. The ports 37 and 78 do not communicate with each other, but are shown l in Figs. 1 and 2 in the same plane of section in accordance with the convention common in the air brake art in order that both ports may be visible in a single more or less diagrammatic view.

A spring 79 urges the piston T5 to the left, and hence assists brake pressure in its action on the piston 75.

Assuming that the motor is running, the reservoirs 13 and 31 will be evacuated. If the valve 59 is in its release position (i. e., to the right as in Figure 1), the cavity 73 will connect the ports 70 and 71, the pressure on opposite sides of the piston 21 will equalize through them, and the spring 23 will move the brake piston to full release position. It; however, the operator should move the brake lever 65 to the right in brake applying direction, the valve 59 would be moved to the left carrying the ports 70 and 71 to the left, so that the port 70 is exposed to atmospheric pressure and disconnected from port 71 (see Figure 2).

Atmospheric air would therefore flow into the left end-s of the cylinders 20 and 20* and move the pistons 21, 21a to the right, applying the brakes against opposition of the spring 23, 23a. i

As pressure inthe left end of the cylinders 20, 20 rises this pressurewill be communicated through the port 78 tothe space at t-he right of the piston 75, and aided by the spring 79 will move the graduating valve 72 to the left until it blanks the port 70, without establishing connection between the ports 7() and 71. The parts will then come to rest in the service lap position ot' Figure 3.

In case the operator should move the lever 65 'to the limit of its motion either from release position or from a partial application position, the parts will ,assume the position shown in Figure 4f. Here the valve 59 is moved so far to the left that the port 70 is carried beyond the-leftmost range of action of valve 72.- This result is secured by limiting the leftward movement of the piston 75 by properly dimensioning cylinder 76. In Fig. 4 the valve 72 is shown in its leftmost position.

Assuming that the brake`-` has been partially or wholly applied, it the operator moves the lever\-65 part way tothe left but not to its extreme left hand, or releasing position, the ivalve 59 will move tothe right,

and the parts will assume a position such as is shown in Figure 5. Here the recess 73 connects the ports 70 and 71, and equalization of pressure on the opposite sides of the pistons 21, 21 commences. This entails a reduction of pressure ,on the left hand side of the pistons 2,1, 21 and this is communicated by the-'port 78, to the space at the lright of therpiston 75,- which piston consepressure equalizing connection between the ports 7 0 and 71 is interrupted, and in which the port `70 is blanked. c

If the brake pedal is restored to release position, as in Figure 1, the ports and 7 1 are again connected, and this connection is maintained because the piston 7 5 is -then arrested at its right hand limit of motion. Consequently, complete release occurs.

It is obvious that the motor vehicle brake may be operated alone, without the trailer brake. In such' case the valves 53 close the couplings 26 and 44 automatically.

Assuming that the vehicle is drawing a trailer, and the train breaks in two, the coupling 44 and the coupling 28 -on-the motor vehicle would be instantly sealed, leaving the brakes on the motor vehicle under the control of the operator. At the same time, the coupling 29 on the trailer will be closed, maintaining the reduced pressure in the supplemental reservoir 30. The coupling 43 on the trailer, however, will not be sealed. The

port 54 permits the gradual admission of air to the left hand side of the piston 21, on the trailer, producinga gradual applica tion 'of the brake and stopping the trailer, so that it cannot run into the leading vehicle.

While I prefer to connect thel system to the intake manifold of the engine, it is obvious that the s stem may be made to work satisfactorily with any other suitable means for evacuating the reservoirs. Similarly, there are certain characteristic features of the brake valve whichare not limited in their utility to a sub-atmospheric pressure brake.

What is claimed is:

1. An application valve mechanism for brake 4systems of the type including a double acting brake cylinder, a reservoir, a reservoir pipe connected with said reservoir and with one end of the cylinder, and a brake pipe connectedwith lthe other end of the cylinder, .said application valve mechanism comprising in combination a valve seat shiftable at will and provided with two ports respectively in constant communication with the brake pipe and reservoir pipe; a valve shiftable on said seat and serving in one position to connect said ports, in another to disconnect them and admit atmospheric air to the brake pipe port, and in an intermediate position to lank both ports; a piston connected with said valve'and subject to atmospheric pressure and'brake pipe pressure in opposite directions, brake pipe pressure urging said valve to the first named position; and resilient means actingon said piston assisting brake pipe pressure.

2. In a brake valve the combinationI of a main application and release valve capable tion port in said main valve su `tion of said vsition to connect said dplgxr,

of being set in 'a release position and in a progressive series vof application positions; a graduating valve controllin an ap lication port in'said main valve su ject to rake c linder pressure and shiftable thereby in t e direction of motion of said. main valve from release through the series of application positions; and means for exerting a resistance to the motion of said graduating valve increasing progressively with the motion of the valve. l

3. An automatic valve for air brakes comp rling in combination a ported shiftable seat; means for shifting said seat at will; a valve movable on said seat and coacting with the ports therein to produce application la and release; a piston connected with sai valve and subject to brake cylinder pressu ur ing said valve toward release position an yielding means resisting such motion oi the valve.

4. An automatic valve for air brakes comprising in combination, a ported vshiftable seat; means for shifting said seat at will a valve movable on said seat and coacting with the ports therein to produce application, lap and release; and a lpiston connected with said valve -to move the same and subject in op ite directions to atmospheric pressure an brake cylinder pressure.

5. In a brake valve the combination of a. main application and release valve capable of being set in a release sition and in a progressive` series of application positions; a graduating valve controlling the ap lical ject to rake cylinder preure and shiftable thereby in t e direction of motion of said main valve from release through a series of application positions; means for limiting such movement of the graduating valve to a range less than the range of movement of the main valve, whereby in the extreme a plication position of the main valve its application port is beyond control by said graduating valve; and means for exerting a resistance to the moaduating valve increasing progressively with the motion thereof.

6. An application valve mechanism for brake systems of the type including a double acting rake cylinder, a reservoir, a reservoir pipev connected with said reservoir and with one end of the cylinder, and a brake pi connected with the other end of the cy inder, said application valve mechanism comprising in combination a valve seat shiftable at will and provided with two rts retively in constant communication with t e brake pipe and reservoir pipe; a valve shiftable on said seat and serving in one poin another to disconnect them and a t atmospheric air to the brake pipe port, and inY an intermediate position to blank both rts; a piston connected with said valve auso subject to atmospheric pressure and brake pipe pressure in opposite directions, brake pipe pressure urging said Valve to the first named position; resilient means acting on said piston assisting brake pipe pressure; and means for limiting the motion of said valve under the combined action of brake pipe pressure and said resilient means to a range less than the range of motion of said valve seat, whereby in the extreme setting of the seat said valve 10 may not lap said brake pipe port.

In testimony whereof I have signed my naine to this specication.

CHARLES ALBERT CAMPBELL. 

